A conventional branched valve has been described in Japanese Patent Provisional Publication (Tokkaisho) No. 151676/87. The branched valve 1 includes a main body 2 provided with a main flow passage 3 and a branch flow passage 4, a weir 5 provided between a branch flow exit 3A of the main flow passage 3 and a branch flow entrance 4A of the branch flow passage 4, and a diaphragm 6 (valve disc) which selectively connects and disconnects the main flow passage 3 and the branch flow passage 4. A branch flow entrance wall 4B of the branch flow entrance 4A which is integrated with the weir 5 has a recessed surface.
However, the conventional branched valve 1 has a disadvantage in that the flux of the branch flow is not sufficient. In the conventional branched valve 1, the branch flow of the fluid which flows into the branch flow passage 4 from the main flow passage 3 is easily peeled off from the branch flow entrance wall 4B just after getting over the weir 5, and makes a turbulent flow. The turbulent flow causes the pressure loss which then causes a large amount of the flux loss.
Further, the conventional branched valve 1 has another disadvantage in that the size is not compact, though the branched valve 1 which is to be connected within i.e. a circulation system of super pure water is desired to has a compact size with sufficient flux of the branch flow. In the conventional branched valve 1, the outer wall of the main flow passage 3 projects largely from the valve center (handle center) to make the width W of the branched valve 1 large, and the lower part of a socket of the branch flow passage 4 projects downward to make the height L of the branched valve 1 large.